When dumping memory the printed addresses always start with `00000000`.
This can be very confusing and lead to errors.
Allow the user to specify a starting address of the printed memory that
will be used instead.
By introducing a wrapper function, existing users are unaffected.
To my knowledge no one was using the more complex functionalities of
this module (except for the test application and pktbuf which just used
the same flags as the `od_hex_dump()` wrapper), so why not reduce the
functionality of this module?
